Added a car to the mix (final version will have trains, planes, and monkeys [probably])

Made the bridge less bouncy

Tested building a bridge across a gap without fixed points

Next:

I'm going to add a "well done, you made it" message thingy

Some sort of explosion for when the top and front of the car experience extreme forces.

Saw an interesting post on the Box2D forums about hanging heavy objects from light objects, and how that's probably a bad thing, so I'll have to check that the bridge doesn't end up doing that during the game.